The Effects of Flattening the Effective Marginal Rate Structure in Australia: Policy Simulations Using the Melbourne Institute Tax and Transfer Simulator

Melbourne Institute Working Paper No. 10/01

Date: October 2001


John Creedy
Guyonne Kalb
Hsein Kew


This paper uses the Melbourne Institute Tax and Transfer Simulator (MITTS) to examine the effects of a reduction in the means-tested benefit taper, or withdrawal, rates in Australia to 30 per cent. That is, all taper rates of 50 per cent and 70 per cent in the 1998 system are reduced to 30 per cent, while leaving all basic benefit levels unchanged. This change is therefore expected to flatten the tax structure by reducing the high marginal tax rates applying to those with relatively low incomes and increasing the marginal tax rates of medium incomes. Simulations in which all individuals are assumed to have an unchanged labour supply (using MITTS-A) are compared with behavioural simulations in which the majority of individuals are free to adjust the number of hours worked (using MITTS-B). The results reflect only the supply side of the labour market. The database used is the 1997 Income Distribution Survey (IDS), so that weekly incomes are based on the financial year 1997-98.

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